1,669 research outputs found
The Low Energy Tagger for the KLOE-2 experiment
The KLOE experiment at the upgraded DAFNE e+e- collider in Frascati (KLOE-2)
is going to start a new data taking at the beginning of 2010 with its detector
upgraded with a tagging system for the identification of gamma-gamma
interactions. The tagging stations for low-energy e+e- will consist in two
calorimeters The calorimeter used to detect low-energy e+e- will be placed
between the beam-pipe outer support structure and the inner wall of the KLOE
drift chamber. This calorimeter will be made of LYSO crystals readout by
Silicon Photomultipliers, to achieve an energy resolution better than 8% at 200
MeV.Comment: 4 pages, 5 figures, in the proceedings of "Frontier detectors for
frontier physics", isola d'Elba, Italy, May 200
Status of the Cylindical-GEM project for the KLOE-2 Inner Tracker
The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as
Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE
phi-factory, will be presented. The R&D includes several activities: i) the
construction and complete characterization of the full-size CGEM prototype,
equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the
2-D readout with XV patterned strips and operation in magnetic field (up to
1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS
beam facility; iii) the characterization of the single-mask GEM technology for
the realization of large-area GEM foils.Comment: 4 pages, 10 figures, Presented at Vienna Conference on
Instrumentation (Feb 15-20, 2010, Vienna, Austria). Submitted to the
Proceeding
A new limit on the CP violating decay KS -> 3pi0 with the KLOE experiment
We have carried out a new direct search for the CP violating decay KS -> 3pi0
with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the
phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x
10^8 KS KL events tagging the KS by means of the KL interaction in the
calorimeter and requiring six prompt photons. With respect to our previous
search, the analysis has been improved by increasing of a factor four the
tagged sample and by a more effective background rejection of fake KS tags and
spurious clusters. We find no candidates in data and simulated background
samples, while we expect 0.12 standard model events. Normalizing to the number
of KS -> 2pi0 events in the same sample, we set the upper limit on BR(KS ->
3pi0 < 2.6 x 10^-8 at 90% C.L., five times lower than the previous limit. We
also set the upper limit on the eta_000 parameter, |eta_000 | < 0.0088 at 90%
C.L., improving by a factor two the latest direct measurement.Comment: Accepted for publication in Physics Letters B (15 pages, 13 figures
Performance of the Muon Identification at LHCb
The performance of the muon identification in LHCb is extracted from data
using muons and hadrons produced in J/\psi->\mu\mu, \Lambda->p\pi and
D^{\star}->\pi D0(K\pi) decays. The muon identification procedure is based on
the pattern of hits in the muon chambers. A momentum dependent binary
requirement is used to reduce the probability of hadrons to be misidentified as
muons to the level of 1%, keeping the muon efficiency in the range of 95-98%.
As further refinement, a likelihood is built for the muon and non-muon
hypotheses. Adding a requirement on this likelihood that provides a total muon
efficiency at the level of 93%, the hadron misidentification rates are below
0.6%.Comment: 17 pages, 10 figure
KLOE results in kaon physics and prospects for KLOE-2
The phi-factory DAPHNE offers a possibility to select pure kaon beams,
charged and neutral ones. In particular, neutral kaons from phi->KS KL are
produced in pairs and the detection of a KS (KL) tags the presence of a KL
(KS). This allows to perform precise measurements of kaon properties by means
of KLOE detector. Another advantage of a phi-factory consists in fact that the
neutral kaon pairs are produced in a pure quantum state (J^(PC) = 1^(--)),
which allowsto investigate CP and CPT symmetries via quantum interference
effects, as well as the basic principles of quantum mechanics.A review of the
most recent results of the KLOE experiment at DAPHNE using pure kaon beams or
via quantum interferometry is presented together with prospects for kaon
physics at KLOE-2.Comment: 5 pages, 4 figures, From Phi To Psi 2011 conference, to be published
in Nuclear Physics B (Proceedings Supplements
Search for dark Higgsstrahlung in e+ e- -> mu+ mu- and missing energy events with the KLOE experiment
We searched for evidence of a Higgsstrahlung process in a secluded sector,
leading to a final state with a dark photon U and a dark Higgs boson h', with
the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with
U decaying into a muon pair and h' producing a missing energy signature. We
found no evidence of the process and set upper limits to its parameters in the
range 2m_mu<m_U<1000 MeV, m_h'<m_U.Comment: 16 pages, 7 figures, submitted to Physics Letters
Limit on the production of a new vector boson in , U with the KLOE experiment
The recent interest in a light gauge boson in the framework of an extra U(1)
symmetry motivates searches in the mass range below 1 GeV.
We present a search for such a particle, the dark photon, in , U based on 28 million
events collected at DANE
by the KLOE experiment. The production by initial-state radiation
compensates for a loss of sensitivity of previous KLOE , searches due to the small branching ratios in
the resonance region. We found no evidence for a signal and set a
limit at 90\% CL on the mixing strength between the photon and the dark photon,
, in the U mass range between and ~MeV. Above 700 MeV
this new limit is more stringent than previous ones.Comment: 6 pages, 9 figures, 1 table, submitted to Phys. Lett.
Measurement of the transition form factor with the KLOE detector
A measurement of the vector to pseudoscalar conversion decay with the KLOE experiment is presented. A sample of signal
events was selected from a data set of 1.7 fb of collisions at
collected at the DANE collider. These
events were used to obtain the first measurement of the transition form factor
and a new measurement of the branching ratio of the
decay: . The result improves
significantly on previous measurements and is in agreement with theoretical
predictions.Comment: 13 pages, 4 figures; matches published versio
Precision measurement of and determination of the contribution to the muon anomaly with the KLOE detector
We have measured the ratio
, with the KLOE detector at DANE for a total integrated
luminosity of 240 pb. From this ratio we obtain the cross section
. From the cross section we determine the
pion form factor and the two-pion contribution to the muon anomaly
for GeV, = . This result confirms the
current discrepancy between the Standard Model calculation and the experimental
measurement of the muon anomaly.Comment: 18 pages, 8 figures, minor text corrections, one table added, version
to appear on Physics Letters
Measurement of {\eta} meson production in {\gamma}{\gamma} interactions and {\Gamma}({\eta}-->{\gamma}{\gamma}) with the KLOE detector
We present a measurement of {\eta} meson production in photon-photon
interactions produced by electron-positron beams colliding with \sqrt{s}=1 GeV.
The measurement is done with the KLOE detector at the \phi-factory DA{\Phi}NE
with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-{\eta}
cross section is measured without detecting the outgoing electron and positron,
selecting the decays {\eta}-->{\pi}^+{\pi}^-{\pi}^0 and
{\eta}-->{\pi}^0{\pi}^0{\pi}^0. The most relevant background is due to e^+e^-
--> {\eta}{\gamma} when the monochromatic photon escapes detection. The cross
section for this process is measured as {\sigma}(e^+e^- -->{\eta}{\gamma}) =
(856 \pm 8_{stat} \pm 16_{syst}) pb. The combined result for the e^+e^-
-->e^+e^-{\eta} cross section is {\sigma}(e^+e^- -->e^+e^-{\eta}) = (32.72 \pm
1.27_{stat} \pm 0.70_{syst}) pb. From this we derive the partial width
{\Gamma}({\eta}-->{\gamma}{\gamma}) = (520 \pm 20_{stat} \pm 13_{syst}) eV.
This is in agreement with the world average and is the most precise measurement
to date.Comment: Version accepted by JHE
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